Stress makes you forgetful, kinase C protein undermines short term memory

According to a new study, stress makes you activate an enzyme in the brain called Kinase C, it is a protein which undermines your short term memory, plus some other brain functions in the prefrontal cortex. The prefrontal cortex is the executive decision making section of your brain.

Ask any actor who is stressed with stage fright, or a student just before an important exam and they will tell you this (losing memory) is old news.


This new study, led by Dr Amy Arnsten, Yale Medical School, USA, has managed to pinpoint why your short term memory is affected when you are experiencing stress.

You can read about this study in the journal Science.

Experts say this study could help scientists and doctors acquire a better insight in how to treat people with bipolar disorder and schizophrenia.

Kinase C (PKC) is an enzyme which is active in patients with bipolar disorder and schizophrenia. Dr. Arnsten found that a psychotic episode often comes after some stressful encounter. Arnsten gave, as examples of stressful situations, leaving home to go to college or joining the armed forces.

Perhaps PKC plays a part in making patients more distracted, impulsive and have bad judgment (common during psychotic episodes).

Perhaps new drugs could target PKC production, said Arnsten.

Dr. Arnsten said 'These new findings may also help us understand the impulsivity and distractibility observed in children with lead poisoning. Very low levels of lead can activate PKC, and this may lead to impaired regulation of behavior.'

In this study Arnsten and team induced stress in rats and monkeys (by administering chemicals). The stress would be similar to what we would feel when exposed to a loud noise, or the jitters we may feel before an exam.

Arnsten said 'It doesn't have to be traumatic, as long as you feel out of control. Control is the essential factor. If you are confident, you don't have these problems." She went on to say that memory and the ability to use abstract thoughts are impaired. 'This kind of memory (using working memory that is constantly being updated), the ability to concentrate, seems to be impaired when exposed to mild stresses.'

Forgetfulness is a tool of the brain

A note to the forgetful: be thankful you don’t remember everything. It means your brain is working properly.

According to a new study, the brain only chooses to remember memories it thinks are most relevant, and actively suppresses those that are similar but less used, helping to lessen the cognitive load and prevent confusion.

Brice Kuhl at Stanford University in California, US, and colleagues used functional magnetic resonance imaging (fMRI) to measure the brain activity of 20 healthy adults while they performed a simple memory test. Participants were given three words pairs to memorise, including two pairs that were closely associated, as follows:

* ATTIC dust
* ATTIC junk
* MOVIE reel

After studying "ATTIC dust" a second time, subjects were asked to recall all three pairs using the first words as cues. On average, people were 15% worse at recalling "ATTIC junk" than they were at recalling the unrelated pair, "MOVIE reel".
Initial suppression

Comparing these findings to the fMRI data taken during the test, the team found participants’ brains were highly active in a region known for handling competing memories, and also in an area believed to induce memory suppression.

The researchers believe that the first region identified "ATTIC dust" and "ATTIC junk" as conflicting memories. The second region then suppressed "ATTIC junk" because it had only been seen once.

As the test was readministered a second and third time, suppression activity lessened, indicating the memory adjustment had been made.
Prioritising memories

"Whenever you’re engaging in remembering, the brain adapts. It’s constantly re-weighting memories," says Kuhl. "In this simple test, we see it reverse memory to weaken competing memories. This is something that probably happens a lot in the real world."

A good example is the confusion that arises when we change passwords on our computers or email accounts. We often mix up old and new passwords at first, but through repetition we develop a strong memory of the new password and forget the old one.

"The process of forgetting serves a good functional purpose," says Michael Anderson of the University of Oregon, US, who was not involved in the study. "What these guys have done is clearly establish the neurobiological basis for this process."

Journal reference: Nature Neuroscience (DOI:10.1038/nn1918)

This article is taken from New scientist website